Late glacial and Holocene vegetation and regional climate variability evidenced in high-resolution pollen records from Lake Baikal

Abstract. A new detailed pollen and oxygen isotope record of the penultimate interglacial–glacial cycle, corresponding to the marine isotope stage (MIS) 7–6, has been generated from the Ahlat Ridge (AR) sediment core at Lake Van, Turkey. The presented Lake Van pollen record (ca. 250.2–128.8 ka) displays the highest temporal resolution in this region with a mean sampling interval of ∼  540 years.The integration of all available proxies shows three temperate intervals of high effective soil moisture availability. This is evidenced by the predominance of steppe-forested landscapes (oak steppe-forest) similar to the present interglacial vegetation in this sensitive semiarid region between the Black Sea, the Caspian Sea, and the Mediterranean Sea.The wettest and warmest stage, as indicated by highest temperate tree percentages, can be broadly correlated with MIS 7c, while the amplitude of the tree population maximum during the oldest penultimate interglacial (MIS 7e) appears to be reduced due to warm but drier climatic conditions. The detailed comparison of the penultimate interglacial complex (MIS 7) to the last interglacial (Eemian, MIS 5e) and the current interglacial (Holocene, MIS 1) provides a vivid illustration of possible differences in the successive climatic cycles. Intervening periods of treeless vegetation can be correlated with MIS 7d and 7a, in which open landscapes favor local erosion and detrital sedimentation. The predominance of steppe elements (e.g., Artemisia, Chenopodiaceae) during MIS 7d indicates very dry and cold climatic conditions. In contrast, the occurrence of higher temperate tree percentages (mainly deciduous Quercus) throughout MIS 7b points to relatively humid and mild conditions, which is in agreement with other pollen sequences in southern Europe.Despite the general dominance of dry and cold desert-steppe vegetation during the penultimate glacial (broadly equivalent to MIS 6), this period can be divided into two parts: an early stage (ca. 193–157 ka) with higher oscillations in tree percentages and a later stage (ca. 157–131 ka) with lower tree percentages and subdued oscillations. This subdivision of the penultimate glacial is also seen in other pollen records from southern Europe (e.g., MD01-2444 and I-284; Margari et al., 2010; Roucoux et al., 2011). The occurring vegetation pattern is analogous to the division of MIS 3 and MIS 2 during the last glacial in the same sediment sequence. Furthermore, we are able to identify the MIS 6e event (ca. 179–159 ka) as described in marine pollen records, which reveals clear climate variability due to rapid alternation in the vegetation cover.In comparison with long European pollen archives, speleothem isotope records from the Near East, and global climate parameters (e.g., insolation, atmospheric CO2 content), the new high-resolution Lake Van record presents an improved insight into regional vegetation dynamics and climate variability in the eastern Mediterranean region.

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Climate variability in the Spanish Pyrenees during the last 30,000 yr revealed by the El Portalet sequence

Quaternary Research ◽

10.1016/j.yqres.2006.02.004 ◽

2006 ◽

Vol 66 (1) ◽

pp. 38-52 ◽

Cited By ~ 149

Author(s):

P. González-Sampériz ◽

B.L. Valero-Garcés ◽

A. Moreno ◽

G. Jalut ◽

J.M. García-Ruiz ◽

...

Keyword(s):

High Resolution ◽

Climate Variability ◽

Climate Changes ◽

Vegetation History ◽

Ice Cores ◽

Late Glacial ◽

Last Glacial ◽

The North ◽

Isotopic Analyses ◽

Spanish Pyrenees

AbstractPalynological, sedimentological and stable isotopic analyses of carbonates and organic matter performed on the El Portalet sequence (1802 m a.s.l., 42°48′00ʺN, 0°23′52ʺW) reflect the paleoclimatic evolution and vegetation history in the central-western Spanish Pyrenees over the last 30,000 yr, and provide a high-resolution record for the late glacial period. Our results confirm previous observations that deglaciation occurred earlier in the Pyrenees than in northern European and Alpine sites and point to a glacial readvance from 22,500 to 18,000 cal yr BP, coinciding with the global last glacial maximum. The patterns shown by the new, high-resolution pollen data from this continental sequence, chronologically constrained by 13 AMS 14C dates, seem to correlate with the rapid climate changes recorded in Greenland ice cores during the last glacial–interglacial transition. Abrupt events observed in northern latitudes (Heinrich events 3 to 1, Oldest and Older Dryas stades, Intra-Allerød Cold Period, and 8200 cal yr BP event) were also identified for the first time in a lacustrine sequence from the central-western Pyrenees as cold and arid periods. The coherent response of the vegetation and the lake system to abrupt climate changes implies an efficient translation of climate variability from the North Atlantic to mid latitudes.

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Quantification of terrestrial regional climate variability from a large database of pollen-based reconstructions and implications for future projections

10.5194/egusphere-egu2020-1203 ◽

2020 ◽

Author(s):

Raphael Hébert ◽

Ulrike herzschuh ◽

Thomas Laepple

Keyword(s):

Climate Variability ◽

Climate Models ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Regional Climate ◽

Irregular Sampling ◽

Large Database ◽

Spatial Correlation Structure ◽

Pollen Records

Multidecadal to millenial timescale climate variability has been investigated over the oceanusing extensive proxy data and it was found to yield coherent interproxy estimates of global and regional sea-surface temperature (SST) climate variability (Laepple and Huybers, 2014). Global Climate Model (GCM) simulations on the other hand, were found to exhibit an increasingly large deficit of regional SST climate variability for increasingly longer timescales.Further investigation is needed to better quantify terrestrial climate variability for longtimescales and validate climate models.Vegetation related proxies such as tree rings and pollen records are the most widespreadtypes of archives available to investigate terrestrial climate variability. Tree ring records areparticularly useful for short time scales estimates due to their annual resolution, while pollen-based reconstructions are necessary to cover the longer timescales. In the present work, we use a large database of 1873 pollen records covering the northern hemisphere in order to quantify Holocene vegetation and climate variability for the first time at centennial to multi-millenial timescales.To ensure the robustness of our results, we are particularly interested in the spatio-temporal representativity of the archived signal in pollen records after taking into account the effective spatial scale, the intermittent and irregular sampling, the age-uncertainty and the sediment mixing effect. A careful treatment of the proxy formation allows us to investigate the spatial correlation structure of the pollen-based climate reconstructions as a function of timescales. The pollen data results are then contrasted with the analysis replicated using transient Holocene simulations produced with state-of-the-art climate models as well as stochastic climate model simulations.Our results indicate a substantial gap in terrestrial climate variability between the climate model simulations and the pollen reconstructions at centennial to multi-millenial timescales, mirroring the variability gap found in the marine domain. Finally, we investigate how future climate model projections with greater internal variability would be affected, and how this increases the uncertainty of regional land temperature projections.

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Radiocarbon Chronology of the Late Pleistocene–Holocene Paleogeographic Events in Lake Baikal Region (Siberia)

Radiocarbon ◽

10.1017/s0033822200035785 ◽

2004 ◽

Vol 46 (2) ◽

pp. 745-754 ◽

Cited By ~ 20

Author(s):

Sergey K Krivonogov ◽

Hikaru Takahara ◽

Yaroslav V Kuzmin ◽

Lyobov A Orlova ◽

A J Timothy Jull ◽

...

Keyword(s):

Late Pleistocene ◽

Lake Baikal ◽

Baikal Region ◽

Late Glacial ◽

Vegetation Changes ◽

Radiocarbon Dates ◽

Lake Baikal Region ◽

Cold Events ◽

Late Glacial And Holocene ◽

Radiocarbon Chronology

New radiocarbon dates obtained from Late Pleistocene and Holocene deposits of the southern, eastern, and northern shores of Lake Baikal in 1995–2001 are presented, and the most important results of paleoenvironmental studies based on C data are discussed. The following paleogeographic events were verified with the help of C dating: 1) first Late Pleistocene glaciation (Early Zyryan); 2) Middle Zyryan interstadial; 3) loess formation during the Late Zyryan (Sartan) deglaciation; 4) warm and cold events in the Late Glacial; and 5) vegetation changes and forest successions during the Late Glacial and Holocene.

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